They could prove a major problem for users who will have to charge up multiple times in a day using the magnetic clip-on charger.

Apple Watch was launched on Monday to much fanfare by Mr Cook, who said that the models will cost between $349 (£231) and $17,000 (£12,000) when they are available next month in the UK on limited release.

He claimed it would be "revolutionary", but now it seems that the battery might be what one tech website described as its "Achilles Heel".

On its website, Apple gave figures for battery life based on the smaller 38mm (1.4 inch) version. The 42mm (1.7 inch) version will last longer, though no figures were given.

Leaving it in reserve mode will last up to 72 hours, and leaving it in "Watch Test" mode will last up to 48 hours.

But should you use any of the features Mr Cook talked about in his press conference, it will last significantly less.

Apple tried to make the figures more impressive by giving an example of a typical user chewing up their 18 hours of battery life as follows: 90 time checks (five per hour), 90 notifications, 45 minutes of app use, and a 30-minute workout with music playback via Bluetooth.

But on the product page of the watch website, it also gave the lower figures for talking or using it to workout.

The Apple Watch was launched by Tim Cook (EPA)

To charge up, users will have to take the watch off and connect the magnetic charger to the back of the device.

They will have to leave it there for one-and-a-half hours to get to 80 per cent full and two-and-a-half hours to get to 100 per cent.

On its website, Apple says: "Battery life varies by use, configuration, and many other factors; actual results will vary."

Batteries have long been an issue with iPhones and iPads with users for both complaining that they drain out after just a few hours.

They have also been an issue with Google’s Glass eyewear - now discontinued in the UK - and when connected to the Internet it lasted just 30 minutes.

Apple Watch Sport, Apple Watch and Apple Edition

By comparison, users of the LG G Watch, which runs Google’s Android Wear system, get two days before it dies.

Writing on Techcrunch.com, Matt Burns said that "Apple clearly does not foresee selling the Watch based on its battery life".

He wrote: "Battery life could be the Achilles heel for the Apple Watch. It’s unquestionably a beautiful and capable device, but if the battery life falls short even a touch from these advertised claims, it will leave many users wearing a device that can just tell the time and not call an Uber (taxi)."

At the Apple Watch launch on Monday, Mr Cook said it will be available in three models: Apple Watch Sport, the Apple Watch and Apple Watch Edition.

Apple Watch Sport is the cheapest and is made of custom silver anodized aluminum whilst Apple Watch is the mid range option and is made of a specially designed stainless steel.

Apple Watch Edition is made of 18 carat solid yellow or rose gold and comes with a gold case and buckle, plus a sapphire crystal protecting the display.

The Apple Watch wirelessly connects to your iPhone and lets you do many of the same functions only without having to reach into your pocket for your mobile.

All three models will do a huge range of things such as checking you in at your hotel, ordering you a taxi or letting you check in to your flight.

The speaker and microphone on the watch let you have a phone conversation or reply to messages via dictation.